its a power point presentation on automatic emergency light using led with complete details of the circuit & the components used to make it along with the advantages, disadvantages & future scope. The slides also contains pcb layout of the circuit.

1. AUTOMATIC EMERGENCY
LIGHT USING LED

2. ABSTRACT
• This automatic emergency led light used in night
at emergency time when the power cut or off by
some region. This emergency light takes 230V
AC and it converts it in 12V DC and charge the
battery which is used in this circuit.
• The power of the battery is used at that time when
the power is cut off or we need to use it. This light
is used mostly in villages because there is the
lack of electricity.

3. BLOCK DIAGRAM

4. HARDWARE EQUIPMENTS
• Transformer(230V-12V AC)
• Rectifier(1N4007 Diodes)
• Filter(1mF capacitor)
• Voltage Regulator(LM317)
• Transistors(BC547,BD140)
• Diodes(1N4007)
• Resistors(16,100,180,1K,1.2K)
• Zener Diode
• LED(5mm white LED)
• Rechargeable Battery

5. CIRCUIT DIAGRAM

6. WORKING
The charger power supply section
It is built around 3-terminal adjustable regulator IC LM317 (IC1). In
the charger power supply section, input AC mains is stepped down
by transformer X1 to deliver 9V, 500 mA to the bridge rectifier,
which comprises diodes D1 through D4. Filter capacitor C1
eliminates ripples. Unregulated DC voltage is fed to input pin 3
of IC1 and provides charging current through diode D5 and limiting
resistor R16. By adjusting preset VR1, the output voltage can be
adjusted to deliver the required charging current. When the
battery gets charged to 6.8V, zener diode ZD1 conducts and
charging current from regulator IC1 finds a path through transistor
T1 to ground and it stops charging of the battery.

7. LED Driver section
The LED driver section uses a total of twelve 5mm white LEDs. All
the LEDs are connected in parallel with a 100-ohm resistor in series with
each. The common-anode junction of all the twelve LEDs is connected to the
collector of pnp transistor T2 and the emitter of transistor T2 is directly
connected to the positive terminal of 6V battery. The unregulated DC voltage,
produced at the cathode junction of diodes D1 and D3, is fed to the base of
transistor T2 through a 1K ohm resistor. When mains power is available, the
base of transistor T2 remains high and
T2 does not conduct. Thus LEDs are off. On the other hand, when mains fails,
the base of transistor T2 becomes low and it conducts. This makes all
the LEDs glow. The mains power supply, when available , charges the battery
and keeps the LEDs off as
transistor T2 remains cut-off. During mains failure, the charging section stops
working & the battery supply makes the LEDs glow. You can use
more LEDs provided the total current consumption does not exceed 1.5A.
Driver transistor T2 can deliver up to 1.5A with proper heat-sink
arrangement.

8. COMPONENTS
• TRANSFORMER- It step downs the voltage from
230v-9v AC .
• BRIDGE RECTIFIER- It converts 9v AC to 9v DC. There
are four 1N4007 diodes used to form a bridge.
• RECHARGEABLE BATTERY- A 6v 4.5Ah lead acid
battery is used to give as o/p.

9. • TRANSISTOR- 1) BC547 is an NPN bi-polar junction
transistor. Its mainly used for amplification and
switching purposes. It has a maximum current gain
of 800. 2) BD140 is a PNP bi-polar transistor. Its
mainly used for medium power linear switching.
• VOLTAGE REGULATOR- LM317 device is an
adjustable three-terminal positive-voltage regulator
capable of supplying more than 1.5 A over an
output-voltage range of 1.25 V to 37 V.

10. • ZENER DIODE- Zener diodes are widely used in
electronic equipment of all kinds. They are used to
generate low power stabilized supply rails from a
higher voltage and to provide reference voltages for
circuits, especially stabilized power supplies.
• FILTER- Capacitor c1 is used as a filter because
capacitors easily pass AC (changing) signals but they
block DC (constant) signals. Here it is used to
eleiminate ripples.

11. • DIODE- a diode is a two-terminal device that
conducts primarily in one direction. Diode 1N4007
has lower voltage drop & high surge current
capability.
• LED- Twelve 5mm high luminous intensity white LED
lights are used having forward voltage(Vf)=3-3.6v &
forward current of 30mA.
• RESISTORS- Various resistors of value
16,180,100,1k,2.2k are used to reduce current flow
& voltage levels at various points in the circuit.

12. PCB LAYOUT

13. PCB LAYOUT WITH COMPONENTS

14. ADVANTAGES
Saves fuel.
 Pollution free.
Easy to use.
Very low cost
Easy to install anywhere
ON/OFF time is quick.

15. DISADVANTAGES
• It can be used only for short period.
• Delectated circuit
• Cool white LEDs can cause problems to eyes.

16. FUTURE SCOPE
• Uses at conference room, exhibition hall
lighting.
• Uses at Direction arrow board for bathroom.
• Long lasting battery that works for approx. 8
hrs.
• Automatic LED can be used for mass
production as cheap & efficient method.